The mechanism of control of synthesis of small nuclear RNAs in sea urchin development will be studied. In addition the possibility of control of synthesis of these RNAs in mouse development will be studied. Using cloned genes for U1 and U2 from both mice and sea urchins we will study the RNA mechanisms of biosynthesis of the mature RNA. The control of synthesis of these RNAs in sea urchin development will be studied using isolated nuclei and extracts prepared from different stages. The expression of different genes for each RNA will be investigated using S1 nuclease mapping to distinguish RNA varients. These studies will help in understanding the control of gene activity at the molecular level.